If you are the type that like very slim and light weight cases, then you might want to take a look at the shell case for the HTC One X. The case is available in blue or orange at the either AT&T retail store or online. The shell case is very light weight and very thin. If you are looking for protection, this is not the case you would want to get for your phone.
I do have to warn anyone that does purchase or is planning on getting the HTC One X shell case, it can break pretty easy.
All the ports and openings line up perfectly with this case, which is great. I have seen and tested cases that sometimes would not line up or fit properly. This is not the case with the shell case. One nice feature about the case is that the word "HTC" lines up perfect on the back of your One X, so that you can show off your "HTC" logo. Very well done!
If your not into blue, you can also pick up the same case in orange which also looks excellent on the white HTC One X. Here is a quick view of the orange shell case and you can see that it is pretty slick.
The shell case is made out of hard plastic, doesn't have the rubberized feeling like some cases to help prevent the unexpected, slipping out of your hand.